Inheritance of Occlusal Topography: A Twin Study

Abstract

Aim-This was to determine the relative contribution of genetic factors on the morphology of occlusal surfaces of mandibular primary first molars by employing the twin study model. Methods-The occlusal morphology of mandibular primary first molar teeth from dental casts of 9 monozygotic (MZ) twin pairs and 12 dizygotic (DZ) twin pairs 4 to 7 years old, were digitized by contact-type three-dimensional (3D) scanner. To compare the similarity of occlusal morphology between twin sets, each twin pair of occlusal surfaces was superimposed to establish the best fit by using computerized least squared techniques. Heritability was computed using a variance component model, adjusted for age and gender.Results-DZ pairs demonstrated a greater degree of occlusal morphology variance. The total amount of difference in surface overlap was 0.0508 mm (0.0018 (inches) for the MZ (n=18) sample and 0.095 mm (0.0034 inches) for the DZ (n=24) sample and were not statistically significant (p=0.2203). The transformed mean differences were not statistically significantly different (p=0.2203). Heritability estimates of occlusal surface areas for right and left mandibular primary first molars were 97.5% and 98.2% (p<0.0001), respectively.Conclusions-Occlusal morphology of DZ twin pairs was more variable than that of MZ twin pairs. Heritability estimates revealed that genetic factors strongly influence occlusal morphology of mandibular primary first molars.

Methodology for Morphometric Analysis of Modern Human Contralateral Premolars

“…In other words, a finding of homolateral premolars with high degrees of similarity had a higher chance belonging to identical twins. Their findings of occlusal topology having less variability in identical twins versus fraternal twins has been confirmed in two three-dimensional geometric morphometric studies [67,68]. Townsend et al speculate that since less asymmetry (both directional and fluctuating) was reported in identical and fraternal twins compared with singletons according to findings made by Boklage, "there may be something special about the twinning process [69,70].…”

A Contribution to the Anatomical Study of the Mandibular Premolars

“…Heredity estimations revealed that genetic factors strongly influence occlusal morphology of mandibular primary first molars. 16 According to Consolaro, epigenetics may explain why teeth of the same patient are not exactly the same on both sides. The genetic information that DNA carries is to develop teeth bilaterally equal.…”

Integrating genealogy and dental variation: contributions to biological anthropology

“…Still, heritability estimates for primary tooth size have confirmed a similarly strong (if not stronger) genetic signature, accounting for well over 50% of observed variation (Di Salvo et al, 1972; Hughes et al, 2000; Mizoguchi, 1998; Townsend, 1980). Outside of metric traits, few heritability estimates have been generated for deciduous teeth, with the exception of crown topography (Su et al, 2008) and orthodontic variables (Chen, 2006; El‐Nofely et al, 1989; Foster & Hamilton, 1969; Harris & Johnson, 1991; Hughes et al, 2001). Deciduous morphology has recently received attention.…”